Treating acute asthma exacerbations in children

Bronchial asthma is one of the most common chronic disorders in childhood. Numerous studies from many different countries have documented a large increase in prevalence of asthma in childhood. The main objectives of asthma management are to control disease activity, evade acute asthma attacks and obtain improved, normal quality of life. Acute admissions to hospital due to acute asthma may be looked upon as the net result of prevalence of the disease in the community, health resources and quality of asthma care.

Acute asthma is in many countries the most frequent cause of admission to hospital during childhood,(1–3) especially during the first five years of life.(2,4) In a study carried out in Oslo, a steady increase in acute asthma admissions was found over a 16-year period. This was especially so for first admissions for acute asthma, which occurred most frequently during the first four years of life. However, readmissions started to decrease from the late 1980s, at the same time as a major increase in the prescription of inhaled steroids as a prophylactic treatment of asthma.(1) This was confirmed in a recently published report from Gothenburg that examined admission data up to 2000.(5)

Acute asthma may be prevented by careful asthma management, but acute asthma admissions are still a problem, especially in young children, and proper hospital treatment procedures for acute asthma remain an important issue.

Clinical presentation and risk for readmission
Causes and presentation of acute asthma exacerbations may vary according to age, as does treatment. Acute asthma exacerbations are most often caused by respiratory viral infections, particularly rhinovirus infections and, in young children especially, respiratory syncytial virus infections, as seen in both a hospital setting and an outpatient setting.(6,7) In older children exposure to inhalant allergens is also important, and Wever-Hess et al recently reported that the presence of specific IgE antibodies to inhalant allergens was a significant risk factor (RR=1.54; 95% CI 1.22–1.95) for readmission to hospital in children older than two years of age.(4) A written management plan for children with asthma is essential, stating both the regular treatment and added treatment in case of exacerbations. When presenting for admission to hospital, the choice of treatment may be influenced by the age of the patient: for example, children 0–2 years of age may be treated differently from older children.

Guidelines and recommendations
Numerous asthma treatment guidelines have been published over the last 10 years, covering both regular treatment and treatment of acute asthma exacerbations, some of which have been updated. Global strategy for asthma management and prevention covers treatment plans both for adults and children, and these guidelines are meant to cover the entire world.(8) Local guidelines and local adaptations of guidelines may be better suited in specific regions, such as the recently published British guidelines,(9) or the Nordic guidelines.(10) During the development of the British guidelines, much emphasis was given to evidence-based recommendations, and the level of evidence for each recommendation is clearly marked.(9) Nevertheless, the therapeutic tradition in different countries affects the guidelines in spite of existing evidence.

Differential diagnosis
Before starting treatment it is important to ensure the diagnosis of acute asthma is correct. Although acute asthma occurs very frequently, there are many differential diagnoses that should be kept in mind. In young infants, acute bronchiolitis has a similar presentation to infantile asthma. Acute bronchiolitis requiring admission to hospital is also a frequent forerunner of asthma.(11) Pneumonia and vascular ring complicated by respiratory infections, as well as other underlying disorders like bronchial foreign bodies, bronchopulmonary dysplasia, ciliar dyskinesia, cystic fibrosis and immune deficiency, should be borne in mind.

Assessment and monitoring
An initial clinical assessment of the acutely ill asthmatic child is important for giving adequate treatment and for the follow-up of the effects of treatment. Both bronchopulmonary status and general condition should be assessed. Numerous schemes for assessment have been published. One way of assessing the degree of bronchial obstruction is given in Table 1.(10,12) It is also important to record respiratory rate, and transcutaneous measurement of oxygen saturation (SpO(2)) has been shown to be useful in early assessment as well for monitoring acute asthma in hospital.(13)

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Hospital treatment of acute childhood asthma
To be able to breathe freely is intimately connected with the feeling of life. Acute breathing difficulties will always be related to fright, and many children say that they have been afraid of dying during their acute asthma attacks. Fright may aggravate the dyspnoea. It is important that health personnel in contact with the patient and the parents behave considerately and are able to convey a feeling of safety. It is now extremely rare for children to die from acute asthma, and when it does occur it is usually due to a lack of realisation of the severity of the asthma attack and hence a delay in initiating adequate measures.(14–16) The usual firstline treatment for acute asthma is bronchodilation with a short-acting inhaled beta(2)-agonist, which may then be supplemented with other treatments as necessary. The firstline treatments presently employed have been used for many years, but the first randomised clinical trial for acute adult asthma with intravenous montelukast, a leukotriene receptor antagonist, was recently published.(17)

The following recommendations are in agreement with the Global Initiative for Asthma (GINA) guidelines,(8) the British guidelines(9) and the Nordic guidelines,(10) unless otherwise stated. However, the approach chosen below is somewhat different from the common guidelines,(18) but is in line with the Nordic Guidelines(10) and is based upon the assessment scale given in Table 1.

Brief guide to the treatment of acute childhood asthma
For assessment scales, see Table 1.

P1–3: There is time for thorough case history and careful clinical examination of the child
Treat with inhaled salbutamol or terbutaline and observe the effect. If necessary repeat the dose after 10 minutes.

If a good effect is obtained and the patient reaches level P0–P1, they may be discharged from hospital with prescribed follow-up treatment every third hour. The parents should be instructed to contact the hospital if the situation worsens. In the case of a less optimal effect, or if the patient rapidly worsens, keep them in hospital and give repeated inhalation every two to three hours.

P4-5: Quickly obtain the major points from the case history; perform necessary clinical examination (observe possible signs of pneumonia, atelectasis or pneumothorax)
Start inhaled salbutamol or terbutaline by nebuliser. Give oxygen by facemask as needed or use oxygen as driving gas for the nebuliser. Prepare an intravenous cannula if needed.

If inhaled therapy is not satisfactory, administer systemic steroid treatment, repeat inhaled beta(2)-agonist and consider inhaled adrenaline (see acute asthma in children 0–2 years of age). Intravenous theophylline may be considered.(19) If the child’s condition improves, then continue surveillance. Without improvement or with unsatisfactory improvement, set up intravenous infusion of fluids, aiming at an adequate hydration level.

If the patient’s clinical condition is not improved by initial therapy, consider preparing transfer to the intensive care unit as soon as the patient is stabilised clinically (circulation and respiration).

P6: Immediate subcutaneous adrenaline, give inhaled salbutamol or terbutaline by nebuliser, give oxygen through facemask
Quick clinical assessment, thereafter treatment as for P4–5. If a good response to the treatment is not obtained, prepare for transfer to the intensive care unit as soon as the patient is stabilised (circulation and respiration). If needed, start intravenous infusion with terbutaline or salbutamol before the transfer.

Assisted ventilation may become indicated, as assessed by the clinical condition (is the patient getting exhausted?) and by transcutaneous (Tc) PaO(2)/Tc PaCO(2)/SpO(2) and arterial blood gases.

Fluid therapy is important in acute asthma. If the patient is not able to get fluid orally, intravenous fluid should be given. Fluid requirement should be met, but the patient should not be overhydrated.

Special considerations for acute asthma treatment in children 0–2 years of age
The principles of treatment of acute infantile asthma are similar to those in older children, namely instant relief with bronchodilating agents and in severe cases anti-inflammatory treatment with systemic steroids.(20) The most frequent differential diagnosis is acute bronchiolitis, although treatment of acute bronchial obstruction is quite similar, and acute bronchiolitis may be the first episode of acute asthma. In young children the bronchial muscular spasm is not so prominent during acute asthmatic attacks as in older asthmatic children. Bronchial mucous secretions and mucosal oedema are more prominent. This has implications for treatment. The symptomatic bronchodilating effects of inhaled beta(2)-agonists are less certain in infants with bronchial obstruction than in older children(21) – a paradoxical deterioration has even been described.(22) On the other hand, a symptomatic effect has been described in several studies of infants with acute bronchial obstruction, either from acute bronchiolitis(23,24) or, in infantile asthma, from the use of inhaled nebulised racemic or l-adrenaline.(25) Even in adults inhalation of racemic adrenaline had similar effects to inhaled salbutamol,(26) as also seen in children 1–17 years of age.(27,28) However, the findings differ. Hariprakash et al did not find that inhaled racemic adrenaline reduced the number of hospital admissions in acute bronchiolitis.(29) It should be mentioned that giving racemic adrenaline outside the hospital setting is usually not recommended, due to the shortlived symptomatic relief and the need for repeated inhalations. Sanchez et al found inhaled racemic adrenaline superior to inhaled salbutamol in a randomised, double-blind study that included both clinical scoring and respiratory mechanics.(30) The positive effect of racemic adrenaline upon lung function in acute bronchiolitis has also been described by the use of other lung function methods.(24) In the recent British guideline,(9) the use of racemic adrenaline has not even been mentioned, whereas in the Nordic consensus racemic adrenaline is recommended as an alternative to nebulised salbutamol.(10) It should also be mentioned that solutions of racemic adrenaline for inhalation (20mg/ml) have accidentally been used for injection, with severe side-effects due to the much higher concentration of adrenaline in the inhalation solution.(31)

Another controversial issue is the use of nebulised solutions compared with metered-dose inhalers (MDIs) in combination with holding chambers. Several studies have demonstrated an equal effect of MDIs and holding chambers to that of using nebulisers.(32,33) A meta-analysis did not demonstrate any significant difference between MDIs with holding chambers and nebulisers in children with acute asthma.(34) The recent guidelines state that both methods can be used.

Conclusion
Acute asthma in infants and children remains a medical emergency, and appropriate assessment and monitoring should be performed in the care of these children. The treatment is complicated with the use of many different drugs by different routes. Each hospital department taking care of such children should have their own written instructions or guidelines for the treatment of acute childhood asthma.